The present invention relates to an optical probe array head device utilized for information recording and reproduction in optical disks and the like.
With an object to further increase the density of optical recording, in recent years, intensive investigations are now under way for conducting near-field optical recording by employing a scanning near-field optical microscope (SNOM). Among them, the method for conducting optical recording by employing an optical probe array prepared by the technology of fine working on a silicon semiconductor is highlighted as a technology which is remedial for the low data transfer velocity as a defect in the recording method using a SNOM.
However, the optical probe arrays of the prior art have such a constitution that the silicon substrate is provided thereon with only a near-field light generating part or, namely, an aperture and the means for optical detection utilizes, as in the prior art, detection of signals by conducting the light condensed by the use of an optical lens system toward a semiconductor optical detector. Since optical lenses are used for both of optical detection and light introduction in this way, a space for containing a built-in lens system or a mechanism for focusing is indispensable so that the device for optical recording is necessarily large and elaborate.
While it is unavoidable that, as the recording density is increased, the recording marks become minute and the intensity of the optical signals consequently becomes feeble, the light-condensing solid angle in the prior art technology is so small due to the use of an optical lens system that the proportion of detectable optical signals is at best only about one tenth of the overall optical signals.
In addition thereto, a position controlling technology such as a tracking control means for accurately tracing the sequence of optical marks, a means for holding the optical probe array always in parallel to the recording medium and so on must be provided but current optical probe arrays are not suitable for such position control.
While a circuit for processing the signals used for the control in various ways must be provided, such a circuit is provided in the prior art separately from the optical probe array so that the device is necessarily large and elaborate and also expensive.
Despite the high data transfer velocity possessed by the optical probe array, as is described above, the optical recording instrument is large and elaborate due to the use of a conventional optical lens system. Further, the light-condensing solid angle is only about 1 sr at best. This value of the light-condensing solid angle means that, as compared with the overall light-condensing solid angle which is 4xcfx80 sr, the proportion of detectable optical signals is only about one tenth of the overall signals so that the emitted optical signals are mostly unutilized.
The technology for position control of optical probe array head such as tracking to accurately trace the sequence of recording marks and the like has not yet been fully established. The fact that the signal processing system is provided separately from the optical probe array is the reason for the device as a whole rendered large and elaborate with expensiveness.
In short, a high data transfer velocity can hardly be accomplished in the prior art recording using the near-field light due to the use of a SNOM. While a high transfer velocity could be expected in an optical probe array with improvements of these defects, following problems must be solved for the practical application thereof.
1) The device is large and elaborate as a consequence of the use of an optical lens system, which is the prior art technology, in the optical detecting part or light-introducing part.
2) While the recording marks are rendered more and more minute as the recording density is increased, the feeble optical signals therefrom cannot be detected with a high efficiency due to the use of an optical lens system.
3) Position control of the optical probe array, such as the tracking technology and so on, cannot be fully undertaken in the prior art technologies.
4) The optical probe array head device is large and elaborate with expensiveness because the optical signal processing circuit is provided externally.
The present invention has an object, in order to solve these problems, to provide an optical probe array head device with omission of the optical lens system necessitated for optical detection.
Another object of the present invention is to provide an optical probe array head device enabling position control such as tracking and the like to accurately trace the sequence of recording marks.
The present invention is to provide an optical probe array head device which is simple and of low costs.
Namely, the present invention provides an optical probe array head device in which the optical lens system indispensable in the prior art technology for optical detection is omitted by providing the optical probe array with an optical detecting part and which enables position control such as tracking and the like to accurately trace the sequence of recording marks by dividing the optical detecting part into a plurality.
In order to solve the above mentioned problems, the present invention provides an optical probe array head device capable of simultaneously detecting a multiplicity of signals coming from a sample or a recording medium by disposing a plurality of apertures which serve as optical probes in an array and by disposing one or a plurality of optical detectors in each of the apertures.
The above mentioned optical detectors provided in the optical probe array are characterized in that they are integrated with the probe array by the fine working technology.
The optical detectors, which are arranged to surround the above mentioned apertures, can detect scattering of feeble near-field light with a high efficiency.
The constitution is such that tracking control is performed by conducting signal processing utilizing the output signals from a plurality of divided detectors obtained by dividing a single optical detector into a plurality.
It is optional that the above described optical probe array is provided with a necessary circuit for processing of signals by utilizing the technology of fine working.